The present invention relates to oil drilling. More particularly, the present invention relates to the monitoring of oil-drilling muds.
In drilling for oil, one of the most important operations is monitoring the drilling "mud" circulated down the well bore and returned to the surface. This mud transports drill cuttings to the surface to keep the well bore open, but of almost as great a level of importance is the information gained about conditions "down-hole" by monitoring various physical and chemical changes that occur as the mud traverses the well bore.
Of particular interest is the fact that the circulating mud incorporates hydrocarbons from the surrounding rock as the drill bit passes. Accurate knowledge about the types and quantities of hydrocarbons revealed as the drill bit penetrates different rock strata is critical to determining how to "bring in" the well as an operating production unit. This operation of determining the hydrocarbon content of the returned mud is one of the more important operations of mud logging. As currently practiced and as taught by the prior art, a sample of gas is extracted from the drilling mud at ground level, using a gas trap. The trap is a metal box immersed in the shale-shaker ditch. Ports in the lower part of the trap allow mud to enter and leave the trap. An agitator motor provides pumping and degassing of mud passing through the trap. The development of a continuous gas trap with good and consistent efficiency has been a high priority in the improvement of mud-logging technology. As presently practiced, the extraction of gas samples from the mud comprises bubbling an extractant gas directly through the mud slurry, then separating the gas from the slurry and cleaning the gas for inputting to the analytical instruments used for hydrocarbon detection, identification, and quantitative determination.
The supported capillary-membrane sampling (SCMS) device is an apparatus characterized by a grooved support member having a tubular membrane, capillary column, or the like supported within the groove of the support member. This apparatus is broadly useful for analytical and/or fluid-separation purposes. Utilization of SCMS technology would allow the elimination of the entire sample extraction--cleanup train. The present invention comprises the use of such technology in monitoring oil-drilling muds.